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Home✈️Aircraft🚁HelicopterRobbe Cuatro - Millennium - Nova - Dyna-X › Electric conversions ... again
03-28-2012 09:52 AM  7 years ago
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trillian

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London, UK

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Electric conversions ... again
I have yet to begin my Milli electric conversion and then recently seeing the SAB goblin made me think. Has anyone done a Futura conversion using a pulley just mounted directly on the motor? That would seem to be the best way to go for the Futura.

I will take the engine and fuel tank off the Milli regardless because I know I'm not going to fly it as a nitro .60. but I want to do a little photo collection of the steps as I go along.

Anyway, I'm just thinking out loud here after seeing those pulleys for the Goblin and I have no idea if the belt width is the same, I suspect it might be narrower, but they make the pulleys in several sizes ready to just bolt straight on a motor shaft.
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03-28-2012 12:05 PM  7 years ago
Markus

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http://www.hpcgears.com/newpdf/timi...leys_5.0mod.pdf

You will need a upper bearing in the top rail, above company is good to deal with, fast shipping. No need for a clutch in my opinion.. Get the corresponding timing belt from any timing belt
supplier for about 10.-to 12.- usd, but get T5 not AT5...

On the Futura you can modify a "gassermount" for easy motor installation...

Best regards
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03-28-2012 12:16 PM  7 years ago
trillian

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Thank Markus,

By the way, what engine is that in the pic in your gallery? (pardon me if I have asked before, I have a terrible memory sometimes).
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03-28-2012 01:14 PM  7 years ago
Markus

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Montreal

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Thats a 160 gemini OS, have sold it in the meantime...
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03-28-2012 08:50 PM  7 years ago
Jason Lewis

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Whitby, Ontario, Canada

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Hello Gents

Trillian, I believe that Bruce Naylor did a conversion, he has some pics in his gallery. Bellow are some of my experiences and ramblings!
Thanks for the link Markus, good stuff.
You say T5 pulley, but all of my belts have AT5 on them, I do not believe they are compatible? The pulleys they have in the range we need are 6mm ID, but I see they can do custom machine work, should be no big deal for them to bore the pulley to 8mm, would not want to trust a 6mm shaft, unless an upper bearing support was used.
I think that it would be OK to run with no upper bearing support with an 8mm shaft.
With a pulley on the shaft it could be kept low, minimizing the leverage. I think that running as short a belt as possible might help as well. My other thought is that it should be possible to mount the motor behind the large pulley, freeing up lots of space in the frame for batteries. One would need to mount the tail servo on the boom to get it out of the way.

I did break a motor shaft on one of my conversions that ran 800 main blades. I had the belt tension too high, trying to stop it from skipping on spool up (with clutch). It was fine in flight. The shaft was from a Hacker motor, installed in a Scorpion 4035-500, all is detailed in my conversion thread. The shaft broke at the c-clip grove next to the top bearing. One idea I have not tried is to use an 8mm shaft with no c-clip grove (such as trex 500 main shaft) this would eliminate this week point if no upper bearing support is used. The problem with the factory clutch stack is that the pulley is at the top, causing lots of leverage on the shaft.

Because of these issues, I plan on re building the conversion in my Robbe Alouette/Lama that swings 800mm blades to a clutch less design in the near future.

The conversion in my thread that ran 690's and the factory clutch, never gave any problems in 100 flight's, so I thought that it would scale up to the 800's with nothing more that a gearing change, but I was wrong!

For a conversion, as a rule of thumb, 10s and a 500kv motor is a very close replacement for a 60 glow. If you want to play with gear rations and motor KV, then Mr. Mel's calculator is on Readyhelis web site, but is also available as an app, and is worth every cent!

Jason
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03-28-2012 09:08 PM  7 years ago
trillian

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Hi Jason,

Yeah, after I posted that I had a look and Bruce had indeed done his with the pulley directly on the motor.

I was thinking exactly the same thing regarding the advantage of having the pulley down on the motor shaft as opposed to the leverage it gets when at the top of the clutch assembly.

I'm not sure the belt length makes much difference but then I'm not a belt expert.

I'll relay that about the shaft breaking on the Aluette conversion because someone I fly with has one and wants to convert it. I don't know how far along in the process he is as yet.

I have casually thought about the idea of the motor being mounted in back outside the frames. This does leave a space that is just big enough for the 6s Turnigy 5000mah packs. So hopefully the C of G would be OK. In theory it should be very close since the LiPos would occupy the same space as the engine but it might be slightly tail-heavy if I were to guess (which could probably be compensated for by moving other things up front).
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03-28-2012 10:35 PM  7 years ago
Markus

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Montreal

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I'm using a Hacker with the long shaft, 6mm with upper bearing support. Due to the forces created by the belt drive, I think you have to use an upper bearing support.
I will use a timing pulley without boss, this way motor moves further up and opens up space for the batteries..
I'm using t5 iso at5 belt , since you cant get pulleys less then 20teeth as at... plus I'm running T belts on most of my machines (nova futura cuatro etc.) without any issues. T belts are easier to get as well, at least in my neck of the woods....
In the end I will convert a Nova, lower frame distance accepts the battery pack better.
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03-29-2012 08:59 PM  7 years ago
Wemo

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Hampton Roads, VA

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Sheryl,

I'm glad you brought this topic up because I want to do a conversion. Markus, what size belt and where do you order it.

Daryl
"How high do they go? Are those things hard too fly? How much do they cost?
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03-29-2012 10:52 PM  7 years ago
Ramster

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NJ

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This is where I get the AT5 pulleys and bar stock:

http://www.brecoflex.com
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03-30-2012 02:00 AM  7 years ago
Markus

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Montreal

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http://www.jasonindustrial.com/About/

But any timing belt store should have most of the dims,
they cut the desired with to order.
price between 10-15 US.( due to small quantities..)

Best regards
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03-30-2012 03:10 AM  7 years ago
Jason Lewis

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Whitby, Ontario, Canada

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Good stuff coming out now!
Markus, is that a gasser mount? If so were did you get it?
Which Hacker motor is that?

Jason
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03-30-2012 04:11 AM  7 years ago
Markus

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Yep its a Gasser mount, I had one in my deep drawers..and
a couple of running Gassers as well.. but thats an other story..

you could buy one from
http://www.ebay.de/itm/Benziner-Mot...=item3cc45521b0

Motor is a 580kv will run on 10s ( bought here on RR, but bell has a runout of over 3 tenth mm, got my money back though)have also a 400kv to run 800mm's on a Nova... I have pulleys 19-26 teeth will have to experiment...

http://www.ebay.de/itm/Neue-Riemenf...=item3cc33bf33c

This handy too... a bid pricey, but good quality.. and this way you are more flexible with your belts.
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04-21-2012 11:56 PM  7 years ago
trillian

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Well, I will make a decision on this soon but at the moment I am pondering three possibilities;

1. My first idea which was to convert a stock Milli 2.

2. Convert my Futura instead.

3. Convert my Dyna-X instead.

The advantage of doing the stock Milli is that the space inside the frames is wide enough to fit the 5000mah Lipos, so they don't have to sit side-by-side saddle bag style as they would on the Dyna-X.

The advantage of converting the Dyna-X or the Futura is that they are both complete flying helis, so all the servos, gyro, RX is in and all setup and trimmed etc. Between the Dyna and the Futura they each have their pros and cons regarding the ease of mounting a motor and placement of everything.

With the Dyna-X I have to pull the engine out now anyway as the rear bearings need replacing, so that got me thinking about these other choices. I have a suitable motor and ESC already (Align 700M and Hobbywing 120HV).

I think between the Futura and Dyna-X the Futura would be just slightly lighter. The other thing about this particular Futura is that it is a bit underpowered with the OS70 engine (which hasn't bothered me really because it is much easier on fuel consumption).
Giving the Futura more power would allow upping the headspeed and giving it a lot quicker response for the aero stuff.

A 20 tooth pulley should give it very close to a 10 to 1 ratio which should be perfect with a 510KV motor. Target governed headspeed would be 1900, 1950 ish for idle-up 2.

Soooooo, 'must think about this... The downside about converting my Futura is that it would mean I would be currently limited by the amount of Lipos I have. I only have two pairs of 6s 5000mah packs. One of the clubs has a generator so I could have packs charging in rotation but anywhere else I go I'd be very limited :-( (I can buy another one and have 3 pairs as I have 5 in total now but realistically 3 pairs is probably about all I can carry around anyway, and this is the biggest problem with big electrics).

On the Futura, I would think if you're mounting a pulley right down on the shaft (this is a 6mm shaft) it wouldn't need an upper bearing block. Surely a 6mm shaft is sturdy enough provided the pulley sits really close to the top of the motor?

----just to add, the SAB Goblin uses a 12.3mm belt, so if they do a 20 tooth pulley that would be an easy way to sort out the pulley for the motor. (The Goblin does not use another bearing block to support the pulley by the way)
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04-23-2012 10:54 AM  7 years ago
trillian

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further thoughts
Having thought about all my options a bit more I have ruled out converting my nitro Futura for the moment because I want to be able to use it to practise hovering moves and will need the flight time.

I don't want to convert my Dyna-X as I think I'd rather keep it as it is for now.

So that leaves two choices; Convert a stock Milli2 or build up another Futura airframe to convert.

The only thng that worries me slightly about converting a Milli is the danger of stripping the main gear if the ESC accidentally engages too fast or something. Those gears may become scarce. The Futura drivetrain on the other hand is very rugged (and I have a lot more Futura spares).

I originally bought the two Milli airframes I have as spares for the Dyna-X.

So, just thinking ahead, has anyone tried fitting an alternative main gear on a Milli ? I'm just worried about jeopardising my limited Milli spares.
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04-24-2012 10:10 PM  7 years ago
Wemo

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Hampton Roads, VA

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Sheryl,

Build a Futura Airframe to convert so I can buy one from you. lol.

Daryl
"How high do they go? Are those things hard too fly? How much do they cost?
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04-24-2012 10:57 PM  7 years ago
trillian

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Hi Daryl,

Well, my long rambling post was me thinking out loud. When I thought more about it I ruled out converting my current nitro helis. So the next thing I started thinking about is the longevity of the main gear on the Milli. I would feel more comfortable about converting one if I know another main gear could be adapted. I think that big gear will last a very long time with a nitro engine powering it behind a clutch but all it takes is one ESC 'brain fart' and the gear is cooked. I have had this happen on a Trex 500 before when the soft start jumped for some reason.

Soooooo, I'm still thinking about the Milli and looking around for an alternative main gear.

I have several Futura drivetrains and various frame halves so I'll start having a think about going that route. It seems pretty simple, just use the gassermount and a 20 tooth pulley from the Goblin, see where the stock belt winds up and if it's just way too long then find a shorter one.

I'd want to fashion some kind of plates on either side for putting straps around the Lipos so need to see where that ends up. (I'm guessing some CF or aluminium strips attached to the gassermount and then attached to posts at the back of the frame, put some vecro on them and strap the Lipos on like saddle bags).
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04-27-2012 12:28 AM  7 years ago
trillian

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I have tracked down a spare Milli main gear so unless I change my mind I will be converting a stock Milli 2.

I have a doner airframe that I bought last year really cheap on Ebay, initially just as spares. It came from a flight training school and had not been run in a few years but was well bult and taken care of.

It has an ali frame but I also have a carbon frame, so I will most likely use the carbon frameset or maybe just the lower frames.

Today I took out the engine and fuel tank. It opens up a massive space.

A quick check with the motor in relatively the spot it will be mounted looks like there's still room underneath it that Lipos can fit anywhere inside the frames. So it will just be a matter of where they need to be for the right C of G.

This is how I got it (came with an OS61LX, Zimmerman pipe, Futaba GV-1 gov, Futaba 501 gyro and S9202 servos);

Here's the empty frame;

And the parts that came out;

I will be removing the 9202s and probably the 501 gyro but I'll leave that for after the motor is mounted.
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05-01-2012 12:43 AM  7 years ago
trillian

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London, UK

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motor mount on the way (hopefully)
A machinist here has volunteered to fabricate a motor mount so with a little luck I will have something in a week or so.

After looking at the various ways to do it I decided the best, not necessarily the easiest, but the best scenario is one continuous aluminium plate that comprises the motor mount and extends over to the main shaft bearing as well. This way you have the most rigid possible relationship between the main gear and the pinion and it adds strength to the frames as well.

I will also be getting a Scorpion 4035 / 450kv motor, so I'll be able to run a 13, maybe 14 tooth pinion.

I havent flown in two weeks now as the weather has been so wet and nasty (they say it was the wettest April since records began! ).
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05-03-2012 03:09 PM  7 years ago
Wemo

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Hampton Roads, VA

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I have several Futura drivetrains and various frame halves so I'll start having a think about going that route. It seems pretty simple, just use the gassermount and a 20 tooth pulley from the Goblin, see where the stock belt winds up and if it's just way too long then find a shorter one
Sheryl...did you find out if the belt will fit? Or what size will it take to make the above combo work? I have the gasser mount and can get the 20T pulley..but no belt
"How high do they go? Are those things hard too fly? How much do they cost?
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05-03-2012 05:12 PM  7 years ago
trillian

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London, UK

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I have not looked into the details on doing a Futura because my first choice was to convert a Milli. My only concern was wanting to have a spare main gear or two and I was able to find one, so I continued just dealing with the Milli.

On the Futura, I don't have a gassermount so I can't check it, but the thing to do is see where the motor shaft is going to sit in the frames and if there's room for it to move back a bit. Then I suppose the thing to do is take an educated guess where the shaft might need to be with a slightly smaller pulley in order to use the existing belt. I think we're only talking about going from 22 or 23 teeth down to 20 so it's not a big move I wouldn't think and if there's space enough between the motor and the back of the mount it should just be a matter of drilling the holes in the mount.
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